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Hey there! Welcome aboard the International Space Station. My name’s Greg Chamitoff. I’m the flight engineer and science officer for Expedition 17. And this idea here, Ask the Crew, hopefully will be a good way for me to interact with everybody down there on beautiful planet Earth. So, submit your questions. Someone will organize them a little bit, send them up to me. And I’ll do my best to give you some answers. And so, we’ll be talking to you.

Greg, why does the Space Station have to be in a specific orientation in order to dock the shuttle or resupply spacecrafts? --
Brian Watt, 42, Phoenix

This is a really good question, and not easy to explain quickly, but I’ll do my best.

Basically what’s happening is the orbital mechanics that’s going on when you fire thrusters with a spacecraft have kind of a strange effect when you look at what the motion is between two spacecraft that are near each other. So for example, if two spacecraft are right behind each other in the same orbit, and the one behind fires thrusters to move forward, what’s going to happen really is that spacecraft is changing its orbit. And the new orbit is going to be an ellipse with a higher apogee, the furthest point away. Halfway around the orbit from the time of thruster firing, the orbit’s going to be a little bit higher. And so what’s going to happen is, 45 minutes later basically at this altitude, what’s going to happen is that spacecraft would move up rather forward towards the spacecraft it’s trying to catch up with. And also since that orbit now is a little bit bigger, it takes longer to go around, and actually it’ll fall behind. So, thrusting forward results in floating up and falling behind, which is very counterintuitive. And a lot of the orbital mechanics effects are kind of like that.

Those are things that happen in the plane of the orbit, but out of the plane it’s suddenly completely different. If you fire a thruster that moves the spacecraft out of the plane of the orbit, what happens is it kind of creates an angle between the two orbits: one of the first spacecraft, one of the other. And, you know, two orbits that are at an angle with each other, they cross each other twice per orbit. So what’ll actually would happen is the spacecraft would move out of the orbit to the side, and then half an orbit later come back and cross over again and go to the other side, and then half an orbit later come back and cross again. So, these are kind of weird things to take into account when you’re trying to manually fly a rendezvous or you’re going to automatically fly a rendezvous.

The in-plane motions and the out-of-plane are different effects from each other. But, there’s a couple of places that you can be, relevant to other spacecraft, where you can stay for awhile and have it not cost you fuel. For example if you’re below another spacecraft, and you’re trying to rendezvous with it, but you want to stay there for awhile, if you’re below, in other words closer to the Earth, you’re in a different orbit; you’re in a different altitude. You’re in a different orbit. And that orbit takes a different amount of time to go around, and you have to apply constant thruster firings, not constant but you have to keep firing thrusters to keep yourself there. So that costs you energy.

One place for sure you can stay, relative to another spacecraft, and not have it cost you any energy to stay there is right in front or right behind, in exactly the same orbit. And so, these are really good places to approach from, because if something goes wrong when the shuttle approaches, if something goes wrong or you want to check that everything is right, right before you finally do your final maneuver to come in, you can have time to stay in that place for awhile, and not have it cost you a lot of fuel to stay there. So that’s one of the main reasons the shuttle approaches from that side.

Theoretically, you could approach from any angle. And for other reasons it’s helpful, you know, if you can stay in the plane, in the orbit plane, you minimize, you know, coupling between axes. Other factors have to do with firing thrusters that might impact parts of the spacecraft, you know, for the space station with the solar arrays. You don’t want to impact the arrays with a thrust exhaust, the plumes from the thrusters. So, a lot of things combine, but essentially it helps to keep things in the orbit plane, and especially in the front and in the back.

Hi up there! I would like to know if you experience any kind of sensory dysfunctions or hallucinations, maybe like little flashes "seen" with closed eyes caused by high energy cosmic radiation? Thank you and greetings from Germany. -- Stephan Hinz, 38, Germany

Well, Stephan, I haven’t had any hallucinations that I know of. I feel pretty normal up here. But I also heard about this idea of being able to see flashes in your eyes when background cosmic radiation hits your retina. And I’ve been kind of hoping to see that.

The thing is, I’m sleeping in a sleep station called the TeSS, the temporary sleep stations, and we have newer ones that are coming up on this next shuttle flight actually. And I think maybe there’s a little more shielding in there, and I might have to try sleeping somewhere else, and see if I can see them. So, I’m still hoping to see that, but so far I haven’t seen it yet.

Well, we already did this once, and one of my crewmates is letting it grow wild. And my commander and I, we gave it a shot and gave ourselves a haircut. I don’t know that we were very successful. But what we have up here, basically, is a trimmer connected to a vacuum cleaner, so that whatever would otherwise fly off gets taken in by the vacuum cleaner.

Actually, tried to do it myself first, and I had marginal success, and then Sergei helped me clean up the mess I was making. And similarly, I gave him a haircut. But, there’s actually a couple of pictures that you could find that we sent down of us giving each other haircuts. I know, didn’t work out so well, but gotta do it.

All right, thanks for the question.

Greg, did your time on Aquarius help prepare you for the time you have spent on the ISS? Or is it totally different? Also, since your crewmates are Russian, do you have to speak Russian to them or do they speak English? Or is it a combination of both? -- Trevor, 34, Alta Loma, Calif.

The undersea habitat "Aquarius" is featured in this image photographed by a
NEEMO crew member during a training session for the NASA Extreme Environment Mission Operations (NEEMO) project. Image credit: NASA

Aquarius is an underwater research habitat that’s located off the coast of Florida, near Key Largo. It’s the only place like it in the world right now, and NASA has a program there called NEEMO, which is NASA Extreme Environment Mission Operations. And the idea of NEEMO was to have something underwater which kind of parallels the kinds of things we do on a space mission and use it as an analog training scenario.

It’s actually a great experience, and, you know, I think of it as a mission in itself and not just training for space station or spaceflight. But, you know, there are a lot of great analogs. You are in an environment that’s going to be pressure controlled. You are dependent on life support systems for everything. Especially going outside, you know it’s a spacewalk and going out with specialized equipment from an underwater habitat, you know, a lot of similarities there.

We did more than that though, we also tried to make our operations there work very much like the way we work on the shuttle following a timeline, having different science tasks or other tasks to do and working with mission control in real time and trying to pass information back and forth for mission control, to and from the station or in that case the habitat. So anyway, I think it’s a really great analog experience for I think, you know, habitat on the moon, the space station, or anyplace where you’re really depending on your own management of a self-contained life support environment for conducting a mission.

So the other question was about speaking Russian. Of course those guys have had to learn English and I’ve had to learn Russian. Their English is, I think, better than my Russian, certainly the commander’s English is better than my Russian. And with the other flight engineer, Oleg Kononenko, we kind of have a mixture. Since there’s two of them and one of me, I try to speak Russian as much as possible. And you know, we speak Russian over dinner and as necessary. Fortunately, Sergei knows enough English to bridge any gaps. So it’s actually a really fun experience up here kind of bouncing from language to language.

So, thanks for the question.

I have always wondered about fire in a zero gravity environment. If you could light a match in your space ship, would the match fire tip go upward as it does down here with gravity, or would it just become a round ball of fire since there is no gravity around the flame? Or, does gravity have any effect on fire? -- Donald Boyer, 66, Ashland, Ohio

That’s a good question and I wish I could demonstrate it for you but they won’t let me light any fires up here unfortunately.

What would happen, the thing that happens on the Earth is that gravity and convection due to the density of air, depending on its temperature, causes the flame as you see it. So in other words, when the fire heats up the air, the air expands and that air that’s expanded now has a lower density than the air that’s around it, so the lower density air floats up. Just like a hot air balloon wants to go up. It’s a volume with a lower density, so the air around it, basically buoyancy pushes it up. So what happens is the hotter air wants to rise and the colder air then comes in beneath the flame and that creates a convection which drives the flame. And of course the air that’s closest to the flame is always hottest, so that convection keeps going and causes the flame to do the interesting things that it does.

Up here, of course the air that is closest to the flame would get hot, but it would have no reason to rise because it’s not lighter than the colder air around it. Gravity is not going to have that effect here. So the hot air, it does expand, and it would basically expand in a ball and it would push the other air away, symmetrically, more or less. So two things from that, one is that you don’t get a flame that rises and looks like a flame on the Earth. But also what happens is that the fire essentially puts itself out, because as the warm air expands, the oxygen is burned up inside that sphere and there is no convection to bring new oxygen back in to where the flame is. So what you would expect here with a flame is that a flame would burn itself out.

Hopefully that’s a benefit for us up here for us with a lot of electrical systems and everything that unless you have some kind of circulation to bring new oxygen to a fire or flame, fires up here generally put themselves out.

Hello, could you describe one of the experiments you performed on orbit and what were the results? -- Marc Mattiuzzo, 22, Lausanne, Switzerland

There are so many things going on up here and they're in different stages.

NASA astronaut Greg Chamitoff, Expedition 17 flight engineer, works with an experiment in the Kibo laboratory of the International Space Station. Image credit: NASA

I am doing several fluids experiments, some medical experiments, Earth observation experiments, there are some experiments running outside for solar observations, material exposure to radiation and vacuum. Then actually cognitive perception experiments to see how our brain behaves in zero gravity. There is something else that’s looking at, sort of like a Star Trek tricorder really, it’s being able to analyze samples on the spot using a portable device rather than having to take some samples or surface samples or air samples or whatever and bring them down to Earth to study later. Being able to analyze the composition of something on the spot is going to be a really important capability for the future.

There are so many but let me pick one to tell you about that I am working on now. It’s a fluids experiment in the Japanese module. It will be the first main experiment there. It’s called MEIS, and what it is, is looking at is called a fluid bridge. So this is a fundamental fluids physics experiment, but it also has amazing applications. I am basically looking at a chunk of fluid, and the fluid is going to be sitting between two metal cylinders, so it’s a cylinder shaped bit of fluid and it’s pretty big so it’s not something you could do on the ground because it would just collapse. Up here it can float and be a relatively large segment of fluid, and there is going to be heating between the two plates. Up here the surface tension has a very dominant effect on fluids, once gravity is not a factor. With heating between these plates, there is going to be a fluid flow that’s also carried by the surface tension. So it’s a very fundamental physics experiment, but it's looking at how fluids behave with a driving force and with surface tension as a mechanism for a flow.

Why is this important? For fundamental physics reasons there's interesting things to understand there, and I am not a specialist in this area, but one of the really neat things about this is we have a lot of things on the ground and in space that depend on pumps and systems that have electronics and sensors and motors to make fluids move around for cooling, for engines, for propulsion. Pumps can fail and things with parts can fail. This experiment has some possible applications for looking at how fluids can move and be forced to move just because of a temperature difference. So we have temperature differences up here, very large temperature differences from inside to outside, from day to night, shadow and sunlight. Huge temperature differences and it's possible to generate flows of fluids just because of these temperature differences. You can imagine a cooling system that works on a space station for a mission to Mars for example. No moving parts, all it would have is tubes. And by exposing these tubes to heating and cooling, you would have the ability to generate continuous flow without any power and any motor.

Anyway, this is one of the possible applications for understanding these mechanisms better. So that’s a pretty neat experiment. We're just getting started. We’ve set up all the apparatuses, and it’s hopefully going to start in the next few days.

I am an avid scuba diver and instructor. As a diver do you feel that your scuba training or experience has had a direct influence on your level of preparedness for space flight? Safe journey! -- Greg, 31, Houston

Absolutely. Completely. In, really, many ways that I didn’t expect. You know, it’s also the same thing for space walk training. You know, we do that training under water in Houston, and there may be a tendency to try to kick when you’re wearing a space suit under water. Obviously it’s not going to do any good up here, but it certainly has made a big difference in familiarity with that environment for training.

But up here inside the space station, I’ve really noticed it too. The funny thing working in zero-G, it’s really convenient. You can do things you couldn’t possibly do, you can get in positions you couldn’t possibly get in to do a task, and when you start thinking in 3-D, you come up with, you know, a better way to do something. It’s good if you can keep that in mind, and allow yourself the freedom to do something a different way because up here you have different options for doing the same task.

But in the same way scuba diving – if you’ve ever done – I’m sure you have – any under water photography, it’s a similar kind of thing. Let’s say you’re trying to take a picture of something under water, your face is in the camera, you’re holding things with your hands, so you don’t have your hands free all the time to grab on to things. Current is pushing you, and you’re trying to hold your body position, hold the camera still, take the picture, and get it done before you turn too far or the current pushes you too far, and you have to readjust everything.

It’s very much like that up here in zero-G. You’re trying to do something, and you push on something to get something done. It moves your body a different way. You’re trying to finish the job before you’re completely upside down and backwards and you have to start all over again. So, actually, like under water photography, for example, is good training for this.

But it is really neat too, also, I think. Scuba diving, you’re used to different orientations, and feeling comfortable maneuvering in different orientations. So, I kind of already felt comfortable with that, floating around here. Although, I think the adaptation up here happens really fast, and floating up here is awesome. It’s even now, three months into it, it’s a blast.

Is it easier to work in space than it is on the ground? -- Chris, 13, England

You know, at first, coming up here, you kind of have to learn how to do everything you already knew how to do again a different way, and so that takes a little bit of doing. And once you get to that point some things are much easier, and other things are harder. Every once in a while, I’m trying to do something, and I just wish I could stand up and hold on to something and keep something still without having to prevent my own body from turning or moving away from what I'm doing.

And if you have a lot of tools and parts you’re working with, the advantage up here is that you can have them floating around you and let go of them temporarily, but the disadvantage is they can disappear really fast. Things seem to want to escape from you up here, and they do escape very quickly, and then you can’t find them.

It is easier to do certain things because you can get in different positions, and you can take advantage of the three-dimensional environment and working in different orientations. And, it’s a lot of fun working in this environment.

My commander, I think, said it best. Sergei Volkov, he and I were talking about this. He was saying, “You know,” he said this in Russian, he said, “You know, working in zero gravity is really great. It’s really helpful,” and he said, “But also, working in zero gravity is really difficult. It’s much harder.” It just depends what you’re doing.

In any case, it’s a lot of fun, and it’s certainly something you could figure out how to do.

Do you have dreams when you go to sleep in the space station? If yes, is it the same compared to the ones you have on Earth? --
Nancy, 51, Florida

Absolutely, yeah. I’m dreaming just like I would on Earth. Sleeping is great up here. It’s really comfortable. Your body just naturally moves into a completely natural position. Your arms kind of float up. They find that kind of in this position is kind of where the neutral position is, and it’s very comfortable. I end up sleeping the whole night and not waking up at all.

What is funny, though, is that you’re used to – I’m used to, you know – the weight of your head on a pillow. There’s something that’s comforting about that. You don’t have that up here, so you can use like a bungee strap and kind of pull your head against the wall - we have basically sleeping bags, and they’re strapped to the wall - and you can put various straps around it to sort of give you something to hold you in place.

What’s funny though is oftentimes, I’m basically in a sleep station, which is kind of like one of these racks we have on the space station, and everything is arranged in there in a certain orientation, sort of an up and down. We’ll have a picture on the wall in there and a computer and other things. But when I sleep, when I wake up, somehow I’m expecting that I’m on my back or lying flat, so all of a sudden, when I get up, when I wake up, I’m disoriented because I sort of think I’m back, and everything, even though it’s right in front of me, I feel like I must be rotated 90 degrees or something. So, waking up, you can still wake up a little disoriented, and that’s kind of strange.

Anyway, sleeping is really wonderful in zero-G. I’m going to really miss that a lot.